A new challenge
A long-time customer, TATA has installed FLSmidth equipment at various sites across India, including iron ore dryers for TATA Steel and soda ash plants for TATA Chemicals. This established relationship led TATA Chemicals to approach us when an existing HGG at a site in Kenya was experiencing frequent failure, due to flame instability and refractory failure. This was resulting in production losses, hitting the plant’s bottom line.
A novel challenge
HGGs are primarily used in the mining and cement industries to supply hot gas within a certain temperature range for the drying or calcining of materials. Although we have installed HGGs previously, this time was to be different. Unlike our previous installations, which were vertical designs, TATA Chemicals required a horizontal HGG. It also required a variable temperature outlet gas range of 800°C-950°C, whereas our HGGs normally operate with a standard outlet gas temperature of 1000°C.
These were significant differences from our standard HGG and required multiple changes to the design – something never done before by FLSmidth. Key changes included increasing the shell thickness of the combustion chamber and adding ribs between the double shell to support the extra loads with additional saddle supports.
FLSmidth were also given a 15-day turnaround time to replace the old HGG, the maximum period for which production at the site could be stopped. Every day the HGG wasn’t functioning would hit TATA Chemicals’ bottom line.
At FLSmidth, meeting our customers’ requirements – however innovative and challenging – is the key to our success. The installation of our first horizontal hot gas generator at TATA Chemicals in Kenya is a perfect example of this.
Meeting the challenges, meeting the deadline
Despite these challenges, we were able to design and manufacture a horizontal HGG for the first time and then install it within the 15-day time period. TATA Chemicals is now enjoying the full benefits of our HGG, which include:
- Better turndown.
- Simple, robust and reliable design.
- User friendly without compromising safety.
- Less weight.
The HGG includes a proprietary FLSmidth oil burner that is designed and sized for the specific project requirements. The oil burner consists of a central FLSmidth OBA nozzle, which uses compressed air for atomisation, and is located inside the turbulator. The oil burner comprises a central high-pressure multi-hole fuel nozzle, surrounded by a combustion air nozzle with swirl vanes for flame stabilisation. Normal turndown ratio of oil is 1:10.
Other design features include the use of heat-resistant steel for all parts exposed to heat, high temperature shock-resistant insulating brick lining of the combustion chamber, separate combustion air fan, dilution air fan and automatic dampers for maintaining a fixed ratio of combustion to dilution air. The air-to-fuel ratio is maintained by a control loop based on flow, giving a constant excess air rate and exit temperature, independent of back pressure.
Providing optimised production
The new HGG was commissioned in August 2019 and the customer has also been closely monitoring the system performance.